IOS开发指南读书笔记11(IOS数据持久层的建立3)

IOS开发指南读书笔记11(IOS数据持久层的建立3)

基于SQLite的数据持久的实现

建立SQLite数据管理

//sqlite数据管理

@interface SQLiteNoteDao : NSObject<BaseNoteDao>

{

sqlite3* _db;

}

#define DBName @"Notes.sqlite3"

@end

为Note添加一个方法

-(id)initWithSqliteStmt:(sqlite3_stmt *)statement

{

self = [super init];

if (self) {

//第二个参数为字段编号从0开始

char* cID = (char*)sqlite3_column_text(statement, 0);

self.ID = [[[NSString alloc]initWithUTF8String:cID] integerValue];

char* cContent = (char*)sqlite3_column_text(statement, 1);

self.content = [[NSString alloc]initWithUTF8String:cContent];

}

return self;

}

具体实现

@implementation SQLiteNoteDao

+(id)sharedManager

{

static dispatch_once_t onceToken;

__block SQLiteNoteDao* instance = nil;

dispatch_once(&onceToken, ^{

instance = [[SQLiteNoteDao alloc]init];

[instance createObjectCacheFile];

});

return instance;

}

-(void)createObjectCacheFile

{

if ([self openDB]) {

char* err;

NSString* createTableSQL = @"CREATE TABLE IF NOT EXISTS Note(ID INTEGER PRIMARY KEY,content TEXT)";

if (sqlite3_exec(_db, [createTableSQL UTF8String], NULL, NULL,
&err)!= SQLITE_OK) {

sqlite3_close(_db);

NSAssert1(NO, @"建表失败,%s",err);

}

sqlite3_close(_db);

}

}

-(NSString *)ObjectCacheFilePath

{

NSString* documentDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

return [documentDirectory stringByAppendingPathComponent:DBName];

}

-(BOOL)openDB

{

NSString* dbPath = [self ObjectCacheFilePath];

if (sqlite3_open([dbPath UTF8String], &_db)!= SQLITE_OK)
{

sqlite3_close(_db);

NSAssert(NO, @"数据库打开失败");

return NO;

}

return YES;

}

-(void)addNote:(Note *)note

{

if ([self openDB]) {

NSString* exeSql = @"INSERT INTO Note(ID,content) VALUES(?,?)";

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(_db, [exeSql UTF8String], -1,
&statement, NULL) == SQLITE_OK) {

sqlite3_bind_text(statement, 1, [[NSString stringWithFormat:@"%d",note.ID]UTF8String],
-1, nil);

sqlite3_bind_text(statement, 2, [note.content UTF8String], -1, nil);

if (sqlite3_step(statement) != SQLITE_DONE) {

NSAssert(NO, @"数据库插入失败");

}

}

sqlite3_finalize(statement);

sqlite3_close(_db);

}

}

-(void)removeNote:(Note *)note

{

if ([self openDB]) {

NSString* exeSql = @"DELETE FRON Note where ID=?";

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(_db, [exeSql UTF8String], -1,
&statement, NULL) == SQLITE_OK) {

sqlite3_bind_text(statement, 1, [[NSString stringWithFormat:@"%d",note.ID]UTF8String],
-1, nil);

if (sqlite3_step(statement) != SQLITE_DONE) {

NSAssert(NO, @"数据库插入失败");

}

}

sqlite3_finalize(statement);

sqlite3_close(_db);

}

}

-(void)modify:(Note *)note

{

if ([self openDB]) {

NSString* exeSql = @"UPDATE Note set content=? and ID=?";

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(_db, [exeSql UTF8String], -1,
&statement, NULL) == SQLITE_OK) {

sqlite3_bind_text(statement, 2, [[NSString stringWithFormat:@"%d",note.ID]UTF8String],
-1, nil);

sqlite3_bind_text(statement, 1, [note.content UTF8String], -1, nil);

if (sqlite3_step(statement) != SQLITE_DONE) {

NSAssert(NO, @"数据库插入失败");

}

}

sqlite3_finalize(statement);

sqlite3_close(_db);

}

}

-(NSMutableArray*)queryAllNote

{

NSMutableArray* datas = [NSMutableArray array];

if ([self openDB]) {

NSString* exeSql = @"SELECT * FROM Note";

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(_db, [exeSql UTF8String], -1,
&statement, NULL) == SQLITE_OK) {

while (sqlite3_step(statement) == SQLITE_ROW) {

Note* note = [[Note alloc]initWithSqliteStmt:statement];

[datas addObject:note];

}

}

sqlite3_finalize(statement);

sqlite3_close(_db);

}

return datas;

}

-(Note*)queryNoteByID:(NSInteger)ID

{

if ([self openDB]) {

NSString* exeSql = [NSString stringWithFormat:@"SELECT
* FROM Note where ID=%d",ID];

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(_db, [exeSql UTF8String], -1,
&statement, NULL)) {

//第二个参数为字段编号从1开始

sqlite3_bind_text(statement, 1, [[NSString stringWithFormat:@"%d",ID]UTF8String],
-1, NULL);

if (sqlite3_step(statement) == SQLITE_ROW) {

Note* note = [[Note alloc]initWithSqliteStmt:statement];

sqlite3_finalize(statement);

sqlite3_close(_db);

return note;

}

}

sqlite3_finalize(statement);

sqlite3_close(_db);

}

return nil;

}

@end